The objective of the proposed research is to provide information about the determinants and functions of problem solving in late adulthood. Middle-aged and elderly persons are being tested on a series of problem solving tasks similar to those used by Jean Piaget with younger age groups. Analyses will focus on patterns of concrete- and formal-operational thought and performance will be examined in relation to health status, initial education, and age. The effects of tasks familiarity will also be assessed. A portion of the total subject-testing quota has been met in the first year, but testing must be continued into the second year. The information provided by this research will ultimately help to expand current conceptualizations of adult cognition and could potentially be used in predicting the performance of older adults in educational and vocational-training pursuits.